//! /system/drivers/display - the generic display engine driver.
//! This driver is a non official driver for GPU vendors like Intel, NVIDIA, AMD. It provides basic
//! display engine features to the display engine protocol used by the display server, compositor
//! and graphical user interface libraries like Zooeee.
//!
//! This driver is acts like BUS driver, in that it detects the GPU, its capabilities and loads
//! sub-drivers for each device detected. Similar The device manager
//! finds display adaptor e.g. over the PCI/ACPI, and passes the buck on to this driver to handle.
//!
//! The display driver provides the low level part of identifying the device and launching the
//! generic device driver for a GPU vendor.
//!
//!  It takes over the framebuffer feature that was setup during system boot.
const std = @import("std");
const device = @import("driver");
const ipc = @import("ipc");
const process = @import("process");
const service = @import("service");
const device_manager = @import("driver");
const logging = @import("logging");
const mmio = @import("mmio");
const display_protocol = @import("display-protocol");
const scanout_protocol = @import("scanout-protocol");
var device_id: u64 = 0;

fn initialise(endpoint: ipc.Handle) bool {
    _ = endpoint;
    // Hello the device manager (role: device — we claim one GPU's PCI function
    // and serve its display engine; we report no children). Best-effort: without a
    // manager the driver still runs standalone; when present, the manager marks us
    // up before the hello deadline and restarts us if we die.
    _ = device_manager.hello(.device, device_id);
    return true;
}

fn onMessage(message: []const u8, reply: []u8, sender: u32, capability: ?ipc.Handle) usize {
    _ = sender;
    _ = capability;
    _ = reply;

    if (message.len < scanout_protocol.request_size) return 0;
    return 0;
}

pub fn main(init: process.Init) void {
    const argument = init.arguments.get(1) orelse {
        _ = logging.write("display: missing device id (argv[1])\n");
        return;
    };
    device_id = std.fmt.parseInt(u64, argument, 10) catch {
        std.log.info("malformed device id '{s}'", .{argument});
        return;
    };
    service.run(256, .{
        .service = .scanout,
        .init = initialise,
        .on_message = onMessage,
    });
}